EXT2 VS EXT3 File Systems

The differences between Ext2 and Ext3 file systems are as follows.

Sl.No	EXT2	EXT3
Journling	No journling	Has journling
Speed of file system(read-write)	Bit faster	Bit slower then ext2 file-system
Data corruption	File system may be corrupted due to unplanned reboots	Prevents file-system corruption
Way to recover data	Require fsck to recover data after unplanned reboot	Does not require(automatic file recovery is done at booting time)
Online file system growth.	By default there is no Online file system growth.	Online file system growth
Commands to format	mkfs.ext2 or mke2fs	mkfs.ext3 or mke2fs -j
Max file size(if block size is 1kB)	2GB	16GB
De-fragmentation	Easy and done with e2defrag	There is no data security when doing de-fragmentation.
Data accommodation	More data can be accommodated in a give space	Less date is written when compare to ext2 in a give space due to journling.

Some FAQ's:

1. What is Journaling?
Ans : In general, Journaling file systems avoid file system corruption by maintaining a journal. The journal is a special file that logs the changes destined for the file system in a circular buffer. At periodic intervals, the journal is comitted to the file system. If a crash occurs, the journal can be used as a checkpoint to recover unsaved information and avoid corrupting of file system metadata.
2.How many file systems supported by linux? and what are they?
Ans : As of now(09-Nov-2009) Linux will supports : Btrfs, cifs, davfs, ext, ext2, ext3, ext4, exofs, hpfs, JFS minix, msdos, ncpfs, NiLFS(2), ntfs, nfs, proc, smbfs, iso9660, sysv, hpfs, affs, ufs, umsdos, vfat, xia, xfs, ZFS.
Note : Please add some more file systems which you people know in the comment section. So that i will update the post with new file systems.

3.What is the maxium size of a paration we can create using ext2 and ext3?
Ans : 4TB paratation can be created in each ext2 and ext3 file system respectively.

4.What is the maxium size of a file we can create in ext2?
Ans : The maximum size what we can create is 2GB to 2TB. It depends on the block size we taken when we are formating. If the block size is 1KB we can not create a file more than 2GB in ext2 file system.

5.What is "ext" in ext2 and ext3?
Ans : When linux first implemented the default file system is minixfs, in subsequent years it was replaced its sucesser file system called extended filesystem. So the naming convention. So ext2 is second version of extended file system. Same explanation is given to ext3 and ext4.

6. Some points about ext4
a.It supports 64 bit storage limits, where as ext, ext2, ext3 are 32Bit storage limits and minix is 16Bit storage limit.
b.Have backward compatibility and performance is improved from lower version.
c.Extents are introduced (An extent is a range of contiguous physical blocks, improving large file performance and reducing fragmentation. A single extent in ext4 can map up to 128MB of contiguous space with a 4KB block size).

And there are many more advantages please see the below links for more info about all the file systems..
http://en.wikipedia.org/wiki/Ext4
http://en.wikipedia.org/wiki/Ext3
http://en.wikipedia.org/wiki/Ext2
http://en.wikipedia.org/wiki/Extended_file_system
http://www.ibm.com/developerworks/library/l-journaling-filesystems/index.html
http://www.oracle.com/technology/pub/articles/calish_filesys.html
http://www.cyberciti.biz/tips/understanding-unixlinux-file-system-part-i.html Please comment your thoughts regarding this post. To give feed back click here.

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